A conventional image transmitting/receiving apparatus or image recording/reproducing apparatus (hereinafter both will be referred to as just image transmitting apparatus) will be described with reference to FIG. 1. First, an input image 11 is encoded by an image encoding unit 12 and the encoded information is sent or recorded to or in a wireless/wired transmission passage 13 or an accumulation medium 14 corresponding to a transmission system. Data obtained on a receiving/reproduction side is decoded by an image decoding unit 15 so as to obtain a decoded image 16.
After the amount of the input image data is reduced to one-severalth to one-several tenths by the image encoding unit 12, the data is sent or recorded. For example, the image data can be lowered to a transmission rate of 1.5 Mbps by MPEG-4 AVC (or H.264) encoding. Because of such encoding, a difference between the decoded image 16 and the input image 11 is recognized as deterioration by a man.
The conventional image transmitting apparatus reduces the amount of the input image data at the time of transmission or recording. Generally, the image encoding standard such as the MPEG-4 AVC (or H.264) encoding has stipulated a method of reducing the data amount effectively without remarkable deterioration for the human visual perception. However, under a limited transmission band width or storage capacity, the detail information of the image is damaged largely. Particularly, when transmitting or recording film images such as movie, film grain information which expresses a large amount of the texture of a movie is lost, so that the quality of decoded image is deteriorated remarkably.
FIG. 2A shows an example of film image applied as the input image 11, and FIG. 2B shows an example of the decoded image 16. As evident from FIGS. 2A and 2B, although the film grain which is detected as the quality of film can be perceived in the input image 21, the decoded image 22 presents a flat image because most of the film grain information is lost. Since the film grain is lost, there is a problem that the film texture cannot be sensed.
Conventionally, Japanese Patent Application Laid-Open (JP-A) No. 11-250246 has stated that the sharpness is stressed by suppressing noises of an image fetched in by a scanner.
The apparatus disclosed in JP-A-11-250246 intends to suppress the grain noise particular to the film image but not to improve the film image texture lost for encoding by high efficiency encoding system on the decoding side.
Accordingly, an object of the present invention is to provide an image processing apparatus and processing method in which loss of film grain information is hardly sensed on the decoding side so as to maintain the film texture of an input image, thereby consequently improving the image quality largely.